Arrangement including means for displaying a charging state
This invention relates to an arrangement which includes charging current generation means which have a first output terminal and a second output terminal and which are arranged to generate and supply a charging current at the second output terminal. The arrangement includes rechargeable energy storage means connected to the second output terminal for charging the storage means, which are rechargeable by the charging current. The arrangement also includes load means which can be connected to the second output terminal and can be supplied with power from the energy storage means.
Such an arrangement of the type as defined in the opening paragraph has been marketed by the applicants, for example, in the form of a mains-independent lady shaver having type no. HP2755/60 and a beard trimmer having type no. HS080, and is therefore known.
The known arrangement includes charging current generation means which, when the appliance is located in an activated charging station connected to a power supply network, is arranged for generating and supplying a charging current to energy storage means to recharge the energy storage means for mains-independent operation, while the arrangement is operating mains-independently outside the charging station. The charging current generation means have a first output terminal with a reference potential and a second output terminal, while the charging current can be delivered via the second output terminal to the energy storage means connected between the first output terminal and the second output terminal. In the charged state and in mains-independent operation, the energy storage means are provided for supplying power to load means. The arrangement further includes switching means for activating and deactivating the power supply to the load means, while the switching means and the load means forming a series combination between the first output terminal and the second output terminal, so that this series combination is connected in parallel to the energy storage means between the first output terminal and the second output terminal.
There is a problem with the known arrangement that when the load means are activated and, above all, when the energy storage means are completely discharged and, consequently, the charging current is delivered to the storage means, a large part of the charging current flows as a detrimental effect as a leakage current through the load means and thus leads to practically no recharging of the energy storage means at all, because the load means have a considerably lower resistance than the energy storage means. For a user of the arrangement this problem causes incomprehensibly and unacceptably long charging times for the charging of the energy storage means.
It is an object of the invention to resolve the problems defined above with an improved arrangement in accordance with the type defined in the opening paragraph.
The object defined in the previous paragraph is achieved with an arrangement of the type defined in the opening paragraph in that the load means and the energy storage means form a series combination between the first output terminal and the second output terminal.
Providing the characteristic features in accordance with the invention advantageously achieves that a leakage current is prevented from occurring in a current path constituted by the load means and running parallel to the energy storage means and that, therefore, when the charging current is applied to the energy storage means by the charging current generation means, the energy storage means are reliably recharged with the charging current.
Providing the characteristic features in accordance with claim 2 advantageously achieves that if the charging current is present for the first switching state of the first switching means, it is avoided that a charging current appears between the first output terminal and the second output terminal and that, if the charging current appears for the second switching state of the switching means, a charging voltage appears which is formed by a voltage drop of the load means and by a time-dependent variable voltage drop of the energy storage means.
Providing the characteristic features in accordance with claim 3 advantageously achieves that when the charging current is present, the charging voltage appearing between the first output terminal and the second output terminal is increased by a substantially constant forward voltage of the diode and that, as a result, a display means voltage can be generated, which is necessary for the charging state display means to operate. A further advantage is obtained in that even if the charging current generation means are supplied with an AC supply voltage, a direction of the charging current is unambiguously defined and that at least during a half wave of the AC supply voltage the display means voltage that is required can be generated.
In an arrangement according to the invention, the charging state display means may be realized, for example, via a incandescent lamp. However, it has proved to be advantageous to provide the characteristic features as defined in claim 4, because they provide energy-saving charge display means. A further advantage is obtained in that the characteristic features as defined in claim 4 provide that the necessary display means voltage can be supplied in an extremely precise manner and that xe2x80x94as soon as the necessary display means voltage is available xe2x80x94a brightness is obtained for a light radiated by the charge display means, which brightness is as constant as possible, even when the energy storage means are being charged, so that, as would be the case with an incandescent lamp, instead of showing the progress of the charging state by a variable brightness of the light radiated by the incandescent lamp, rather the actual charging of the energy storage means is shown. Furthermore, a suitable choice of a type of the light-emitting diode with a suitable forward voltage provides a display means voltage that is required, so that even for the case where the energy storage means are fully discharged, already a reliable indication of the charging of the energy storage means is obtained when the charging current appears and when the second switching state of the switching means is there.
Providing the characteristic features as defined in claim 5 advantageously achieves that even when an amplitude of the AC supply voltage exceeds a blocking voltage of the light-emitting diode, the display means for the charging state can be realized by the light-emitting diode.
The aspects defined above and further aspects of the invention become evident from the example of embodiment to be described hereinafter and will be explained with reference to these examples of embodiment.